A typical base station may include a digital unit, a radio unit, and an antenna. The digital unit may be referred to as a baseband unit. Such a typical base station has a structural limitation to optimize a cell design. Accordingly, a distributed antenna system has been introduced. In the distributed antenna system, a plurality of antennas is spatially separated from the base station and distributedly installed at various locations, for example, each floor of an office building. Such a plurality of antennas may be connected to a radio unit in the base station. The distributed antenna system may enable various cell designs and reduce coverage holes. The distributed antenna system, however, may have a limitation in maximizing system capacity.